Showing papers by "W. M. Wonham published in 1988"
01 Apr 1988
TL;DR: The observability of discrete-event systems is investigated and a solution of the supervisory control and observation problem (SCOP) is obtained.
Abstract: The observability of discrete-event systems is investigated. A discrete-event system G is modeled as the controlled generator of a formal language L m ( G ) in the framework of Ramadge and Wonham. To control G, a supervisor S is developed whose action is to enable and disable the controllable events of G according to a record of occurrences of the observable events of G, in such a way that the resulting closed-loop system obeys some prespecified operating rules embodied in a given language K. A necessary and sufficient condition is found for the existence of a supervisor S such that L m ( S/G ) = K . Based on this condition, a solution of the supervisory control and observation problem (SCOP) is obtained. Two examples are provided.
834 citations
TL;DR: In this article, a modular approach to the synthesis of supervisory control for discrete-event systems is presented, where the basic problem is to ensure by appropriate supervision that the closed-loop behavior of the system lies within a given legal behavior.
Abstract: We examine a modular approach to the synthesis of supervisory controls for discrete-event systems. Discrete-event systems are modelled by automata together with a mechanism for enabling and disabling a subset of state transitions. The basic problem of interest is to ensure by appropriate supervision that the closed loop behavior of the system lies within a given legal behavior. Assuming this behavior can be decomposed into an intersection of component restrictions we determine conditions under which it is possible to synthesize the appropriate control in a modular fashion.
409 citations
01 Apr 1988
TL;DR: The paper develops the idea of local supervisors Si whose concurrent operation results in the closed-loop language L( ΛS i /G ) and conditions are obtained which guarantee that distributed local supervision is equivalent to global supervision.
Abstract: A discrete-event system G is modeled as the controlled generator of a formal language L( G ) , in the framework of Ramadge and Wonham. In general a centralized global supervisory controller S for G can be defined which generates a suitable closed-loop languageL(S/G). The paper develops the idea of local supervisors Si whose concurrent operation results in the closed-loop language L( ΛS i /G ) . Conditions are obtained which guarantee that L( ΛS i /G ) = L( S/G ) , namely, distributed local supervision is equivalent to global supervision. For illustration a simple manufacturing system is discussed.
318 citations
07 Dec 1988
TL;DR: It is shown that a predicate can be synthesized by a static state-feedback controller utilizing only partial state information if and only if the predicate is both controllable and observable.
Abstract: A discrete-event system (DES) is described by a state-transition model. By disabling and enabling controllable events according to a rule based on partial information about the current state of the system, a static state-feedback controller synthesizes a predicate specifying states reachable from the initial state in the controlled system. Concepts of controllable predicate and observable predicate are introduced. It is shown that a predicate can be synthesized by a static state-feedback controller utilizing only partial state information if and only if the predicate is both controllable and observable. Some general results are presented for a state-variable model of a controlled DES. >
97 citations
TL;DR: It is shown that a closed-loop supervisory control has `correct' real-time behavior if and only if the supervisor is well-posed (with respect to time delay).
51 citations
07 Dec 1988
TL;DR: This study extends the authors' previous results on decentralized supervision and supervision under partial observations by incorporating both these features in the control structure by introducing a concept of coordination.
Abstract: Decentralized supervision and coordination are studied for partially observed discrete-event systems. This study extends the authors' previous results on decentralized supervision and supervision under partial observations by incorporating both these features in the control structure. In addition, a concept of coordination is introduced, and conditions for the existence of a coordinating supervisor are established. The ideas are illustrated by application to a simple model of a manufacturing system. >
37 citations
TL;DR: A method for the specification of a supervisor for a discrete event system in terms of a legal constraint language which is defined in termsOf illegal states and event sequences is proposed, which is a natural manner for the Specification of mutual exclusion and synchronization requirements.
Abstract: In this paper, a method for the specification of a supervisor for a discrete event system in terms of a legal constraint language which is defined in terms of illegal states and event sequences is proposed This is a natural manner for the specification of mutual exclusion and synchronization requirements A procedure for the synthesis of a supervisor which enforces the legal constraint language is also discussed
31 citations